Any one know what this does? 2000 subaru legacy

Thanks David This car is UK spec and has a rear wiper / defroster separately on the end of the wiper stalk and a switch for the defroster. This is why its so confusing , been using it when frosty and nothing has exploded or shorted out so ............

It could be for heated wiper blades - http://www.autoanything.com/winter- driving/Subaru/111A53020A54532A0A28A0A1.aspx

this is for heating of the front wipers. on European models and Japanise they have this. in our country it's a everyday procedure in winter. especially helpes when you are on the long road trip using your wipers all the time. don't be affraid to to turn it on! just make sure you have the original front window with 3-4 heater stripes.